Electrical Tuning of Plasmonic Conducting Polymer Nanoantennas.

Nanostructures of conventional metals offer manipulation of light at the nanoscale but are largely limited to static behavior due to fixed material properties. To develop the next frontier of dynamic nano-optics and metasurfaces, this study utilizes the redox-tunable optical properties of conducting polymers, as recently shown to be capable of sustaining plasmons in their most conducting oxidized state. Electrically tunable conducting polymer nano-optical antennas are presented, using nanodisks of poly(3,4-ethylenedioxythiophene:sulfate) (PEDOT:Sulf) as a model system. In addition to repeated on/off switching of the polymeric nanoantennas, the concept enables gradual electrical tuning of the nano-optical response, which was found to be related to the modulation of both density and mobility of the mobile polaronic charge carriers in the polymer. The resonance position of the PEDOT:Sulf nanoantennas can be conveniently controlled by disk size, here reported down to a wavelength of around 1270 nm. The presented concept may be used for electrically tunable metasurfaces, with tunable farfield as well as nearfield. The work thereby opens for applications ranging from tunable flat meta-optics to adaptable smart windows.